Check my edit. He campaigned for him after his first term (through which he actively opposed him), and only really saw him as an ally after the first 3 years through the civil war (and after Lincoln's own perspective had shifted).
Edit: keep in mind that Lincoln signed the emancipation proclamation January 1st of 63, before Douglass had any interest in campaigning for him. He had literally already abolished slavery before Douglass threw his hat in for him
I had to go and pull out my copy of Blight's book on Douglass, because it had been a while but I remembered that section of the book differently.
The whole passage is expressing a sentiment very different from the one that 'Grunge' article is representing - without transcribing that whole section i'll just quote the last little bit that summarizes his summer leading up to the election:
spoiler
The comparison is not quite as clear as I think you'd like, since Douglass's tentative 'support' of Lincoln was motivated by a desire to bring the north and south closer to outright conflict, not as a way of picking a lesser evil or mitigating harm. I'd say Douglass's sentiment is more in-line with current-day pro-palestinian activists, who acknowledge the political calculus of a moderately-favorable party against an outright hostile one, but who publicly oppose voting for them themselves. He'd be in that same 'protest-vote' pool that most people here keep complaining about. I'm actually lightly amused by this apparent reversal, since today it's more common to find people who say 'i will vote for democrats' but then actively campaign against them, but again I think the comparison is strained.
Either way, trying to argue that Douglass 'worked for Lincoln' is still incredibly misleading at best, and clearly a liberal self-centeredness that he (and most other black civil rights activists in our history) actively loathed and berated:
Doubtless he wouldn't have seen as much in the way of redeeming qualities in Biden or Harris, since far from Lincoln's willingness to engage the south (for the wrong reasons in Douglass's mind), Biden repeatedly cowered away from confronting Israel's antagonism and actively sheltered them from consequence. But then again I think neither of us can do more than speculate as to what he'd think of us more than 170 years later.